This invention relates generally to the field of medication delivery systems and, more particularly, to flexible needle assemblies for use with medication delivery pens.
Medication delivery pens, such as hypodermic syringes, are used for self-injection of precisely measured doses of medication and are widely used, for example, by diabetics to dispense insulin. Medication delivery pens may also be used to inject human growth hormone as well as other types of liquid medication into a patient.
A typical prior art medication delivery system includes a pen having a cartridge, a plunger and a needle assembly. The pen is typically fabricated from a plastic or polymer material and has generally a tubular structure that is approximately the dimensions of a conventional writing pen.
The cartridge, which contains a volume of liquid medication, is generally an elongated tube of glass or plastic that has a pierceable rubber septum extending across a distal end of the cartridge.
The plunger is used to urge the medication, which is stored in the cartridge, out of the distal end of the cartridge.
The needle assembly includes an elongated needle cannula having opposed proximal and distal portions. The cylindrical wall of a needle hub surrounds the proximal point on the needle cannula and includes an array of internal threads for engaging external threads on the neck of the pen cartridge retainer or an adaptor.
Syringe systems as disclosed in U.S. Pat. Nos. 5,599,323 (Bonnichsen et al.) and 5,462,535 (Bonnichsen et al.) relate to a syringe system having a pen shaped syringe with a cartridge containing insulin and an injection needle.
U.S. Pat. No. 5,951,530 (Steengaard et. al.) relates to an injection needle mounted in a needle hub fitting onto an injection device from which preset doses of medicine from a cartridge accommodated in the device is administered.
U.S. Pat. No. 3,884,230 (Wulff) relates to a flexible needle and guard device for a hypodermic syringe. The device includes a flexure tube interconnected between the syringe and the needle. However, the Wulff device has a flexible needle, rather than a flexible hub.
One disadvantage to conventional medication delivery pens as disclosed in the prior art is that some patients may have a tendency to inadvertently move or otherwise jitter the needle assembly while injecting the medication. This can cause pain and/or skin trauma because the piercing procedure is not as precise as possible.
Accordingly, there is a need in the art for an apparatus and method that reduce the pain and skin trauma associated with unintended motion of a needle assembly while injecting medication.
There is also a need for an apparatus and method that permit the needle cannula to move about the centerline of the hub of a needle assembly.
Accordingly, one embodiment of the present invention is directed to a needle assembly for use with a medication delivery pen. The needle assembly has a needle cannula with a proximal portion and a distal portion. A hub, to which the needle cannula is mounted, includes a flexible roof portion. The flexible roof portion permits the needle cannula to move about the centerline of the hub.
Another embodiment of the present invention is directed to a medication delivery system that includes a medication delivery pen and a cartridge containing medication. The cartridge is disposed within the medication delivery pen. A needle assembly is engageable with the cartridge and includes a needle cannula and a hub. The needle cannula has a proximal portion and a distal portion. The needle cannula is mounted to the hub, which includes a flexible roof portion, which permits the needle cannula to move about the centerline of the hub. Thus, the medication can flow through the needle cannula during an injection procedure.
Yet another embodiment of the present invention is directed to a method of operating a medication delivery system. The method includes attaching a needle cannula, which has a proximal portion and a distal portion, to a hub. The hub includes a flexible roof portion. Next, the proximal portion of the needle cannula is coupled to a cartridge containing medication. The cartridge within the medication delivery pen dispenses medication. The next step is to inject the distal portion of the needle cannula into a patient and deliver the medication into the patient. The flexible roof portion of the hub permits the needle cannula to move about the centerline of the hub.
Yet another embodiment is directed to a needle assembly in which the hub and cannula are disposed in a ball-and-socket relationship. This ball-and-socket relationship permits the cannula to rotate relative to the hub.
The invention will next be described in connection with certain exemplary embodiments; however, it should be clear to those skilled in the art that various modifications can be made without departing from the spirit or scope of the claims.